This study aimed to evaluate the performance of 46 maize lines (S4) obtained from crosses between the commercial hybrids Penta x P30F53 in topcrosses with the commercial simple cross hybrid Dow8460 (tester) and checks (hybrids Penta, P30F53, Dow8460 and Status). The grain yield was evaluated in two environments in Guarapuava, Paraná State, and the effects of genotype, environment and genotype x environment interaction were significant. The grain yield of the topcross hybrids ranged from 8,416 to 13,428 kg ha-1. The agronomic characteristics of the forage and the bromatological characteristics of the silage were evaluated in environment 1. The green mass yield of the forage ranged from 48,767 to 87,714 kg ha-1 and the dry mass yield ranged from 14,749 to 26,130 kg ha-1. The neutral detergent fiber content ranged from 44.85 to 58.45% and the acid detergent fiber content ranged from 28.28 to 37.06%. The relative feed value of the silage ranged between 100.5 and 138.5. The tester, hybrid Dow8460, was efficient to discriminate the relative performance of the S4 lines in the topcrosses.

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Strawberry shows genetic variability between cultivars and, environmental elements affect the physicochemical traits of fruits when assessed under different environments. So, assessment of the stability of physicochemical traits is a tool that assists the producer in the choice of the cultivar with higher acceptance in the consumer market. This study aimed to assess the stability of strawberry cultivars based on physicochemical traits of fruits on three environments using the additive main effects with multiplicative interaction (AMMI) analysis. Thirteen strawberry cultivars were assessed in Lavras-MG, Uberlândia-MG, and Guarapuava-PR. The experimental design was in blocks with treatments at random and four replications. The stability of physicochemical traits of fruits (firmness, soluble solids, titratable acidity, soluble solids to titratable acidity ratio, vitamin C, and anthocyanins) was assessed. For the stability and performance of physicochemical traits under the three environments, the cultivars Tudla and Festival stood out for fruit firmness, Albion for soluble solids, Aromas and Tudla for titratable acidity, Sweet Charlie and Palomar for soluble solids to titratable acidity ratio, and Camarosa for vitamin C and anthocyanins.

The strawberry is susceptible to several pests which cause a reduction in productivity. The use of mechanisms which repel or prevent these pests to establish, represent a sustainable environmental technology to reduce the frequency of agrochemical use. In this context, the aim of this study was to evaluate the effect of salicylic acid (SA) on resistance induction against two-spotted spider mite in strawberry cultivars (Aromas and Sweet Charlie). Five concentrations of SA (0, 25, 50, 75 and 100 mg L-1) were tested in order to verify the antixenosis effects. In SA concentration of 50 mg L-1, a reduced number of mites in the two strawberry cultivars was noticed. For the number of eggs deposited on leaflet, we verified an effect of SA concentration with quadratic adjustment in the equation. Sweet Charlie cultivar was more effective than Aromas in relation to the reduction of mite oviposition on leaflets treated with SA. SA concentrations of 25, 50 and 75 mg L-1 were the most efficient for the evaluated traits allowed to infer its potential as antixenotic resistance inducer against two-spotted spider mite in strawberry crop.

Resumo: Época de semeadura e ponto de corte de plantas de milho forrageiro são fatores importantes na produção de forragem de alto rendimento. O objetivo deste trabalho foi avaliar a participação dos componentes da planta em diferentes épocas de semeadura e estádios de colheita, em híbridos comerciais de milho recomendados para produção de forragem. O delineamento foi em blocos casualizados, com três repetições, esquema fatorial 4x2, sendo quatro híbridos de milho (P30B39H, DKB245, 2B688H e DKB330Y) e duas épocas de semeadura (outubro e novembro). O experimento foi conduzido no município de Guarapuava, PR. As avaliações foram realizadas nos estádios R4 e R5, sendo avaliados a porcentagem em matéria seca da folha (PPFOL), colmo (PPCOL), brácteas e sabugo (PPSAB), e grãos (PPGR) por meio de fracionamento da planta. O hibrido DKB245 apresentou menor participação de folhas, colmo, brácteas e sabugo, e maior participação de grãos nos estádios reprodutivos grãos farináceos e grãos farináceos duros, independente da época de semeadura. Com o avanço do estádio reprodutivo grãos farináceos para grãos farináceos duros houve elevação do percentual de grãos nos híbridos avaliados e redução na participação de folhas, colmos, brácteas e sabugo, nas duas épocas de semeadura (outubro e novembro). No estádio grãos farináceos duros os genótipos avaliados foram menos influenciados pelo efeito da época de semeadura, tendo maior participação de grãos para todos os genótipos, sendo a época indicada para a colheita da forragem. Palavras-chave:Forragem. Fragmentação da planta. Ponto de colheita. Zea mays L. Abstract:The sowing dates and harvesting times of forage maize are important factors in high-yield forage production. The objective of this study was to evaluate the participation of plant components for different sowing dates and harvest stages, in commercial maize hybrids recommended for the production of forage. The experimental design was of randomised blocks, three replications, in a 4 x 2 factorial scheme, being four maize hybrids (P30B39H, DKB245, 2B688H and DKB330Y) and two sowing dates (October and November). The experiment was carried out in Guarapuava, in the state of Paraná, Brazil (PR). Evaluations were done at stages R4 and R5, when the percentage of dry matter was evaluated by means of fractionation for the leaves (PPFOL), stem (PPCOL), grain (PPGR), and bracts and cob (PPSAB). The hybrid DKB245 displayed less participation of the leaves, stem, bracts and cob, and a higher participation of grain at the farinaceous and hard farinaceous grain reproductive stages, irrespective of sowing time. With the advancement of the farinaceous grain reproductive stage to hard farinaceous grain, there was an increase in the percentage of grain in the hybrids under evaluation and a reduction in the participation of the leaves, stem, bracts and cob for the two sowing dates (October and November). At the hard farinaceous grain stage, the genotypes under evaluation were less influenced by the effect of sowing time, there being a greater p...

Gas exchanges in species and interspecific hybrids of tomato in different environments may contribute to the development and selection of genotypes with a higher tolerance to adverse cultivation conditions. This study aimed to assess the photosynthetic characteristics of wild tomato species and the cultivar Redenção, as well as the respective F1 hybrids of interspecific crosses cultivated under two environments. The experimental design was a randomized block design with three replications and the assessment of six wild accessions, one cultivar, and the respective interspecific hybrids under two environments. At 14, 28, 42, 56, and 70 days after transplanting (DAT), gas exchange characteristics were assessed by means of a portable photosynthesis measurement system. The stomatal density of abaxial and adaxial surfaces of first-order leaflets was estimated under a protected cultivation at 56 DAT. We observed a higher influence of wild tomato species and interspecific hybrids on the assessed characteristics when compared to the cultivation environments. The accession ‘LA-716’ and the hybrid ‘Redenção’ × ‘LA-716’ presented the highest water use efficiency and the accessions ‘PI-127826’ and ‘PI-134417’ and the interspecific hybrids ‘Redenção’ × ‘PI-127826’ and ‘Redenção’ × ‘PI-134417’ presented the highest values of CO2 assimilation, transpiration, instantaneous in vivo carboxylation efficiency of Rubisco, and number of stomata on the abaxial leaflet surface. Thus, the descendants of Solanum habrochaites are an interesting alternative to breeding programs that aim to make advances in obtaining strains that exhibit improvement in their photosynthetic characteristics.

Tomato crop presents several obstacles that hinder its cultivation, especially the tomato leafminer Tuta absoluta (Lepidoptera: Gelechiidae). To reduce damages caused by this pest, the development of resistant cultivars is one of the main alternatives. In this study we aimed to select tomato genotypes with high acylsugar contents and resistant to tomato leafminer. For this, contrasting F2RC1 genotypes for allelochemical contents, resulting from the interspecific cross between cultivar Redenção with processing characteristics, and the wild species Solanum pennellii accession ‘LA-716’, with high acylsugar contents, were submitted to a test of resistance to tomato leafminer with 14 treatments, being eight genotypes with high acylsugar content and four with low acylsugar content, in addition to the parental. Significant correlations and contrasts were observed between acylsugar contents and traits related to the resistance to tomato leafminer. The genotype RVTA-2010-31-pl#177 presented similar behavior to the wild parental, demonstrating potential to advance in the tomato breeding program for industrial processing with resistance to tomato leafminer.

Considering the aforementioned information, the objective was to evaluate the influence of combining techniques of solarization, biofumigation with chicken manure and grafting on the incidence of bacterial wilt and productivity of the hybrid tomato ‘Absoluto’. Two experiments were carried out in a chapel-type greenhouse and in field, in the agricultural year 2013/2014, in a commercial farm on the municipality of Barra do Rio Azul-RS. In the two cultivation environments, treatments were arranged in randomized block experimental design, with the plots subdivided into space and treatments randomly arranged, in an area naturally infested with race 1, biovar 1, phylotype II of R. solanacearum. The treatments were soil solarization, biofumigation, biofumigation +solarization and control, and in the subplots, the commercial hybrid tomato Absoluto with and without grafting on the hybrid rootstock Guardião. Based on the incidence of bacterial wilt, the plant health index and the area under the disease progress curve were estimated. The number, production and average mass of commercial fruits were evaluated. A beneficial effect was found of soil solarization associated with the addition of chicken manure in the control of bacterial wilt and increase of productivity. Grafting was more efficient in increasing plant health index and reducing the area under the disease progress curve than solarization and biofumigation, thus indicating that the association of the three measures is beneficial to the integrated control of the disease